It is known to use vibrating meters to measure mass flow and other information of materials flowing through a pipeline. One particular type of vibrating meter is a vibrating Coriolis flow meter as disclosed in U.S. Pat. No. 4,491,025 issued to J. E. Smith, et al. of Jan. 1, 1985 and Re. 31,450 to J. E. Smith of Nov. 29, 1983. These vibrating meters have one or more fluid tubes. Each fluid tube configuration in a Coriolis mass flow meter has a set of natural vibration modes, which may be of a simple bending, torsional, radial, lateral, or coupled type. Each fluid tube is driven to oscillate at resonance in one of these natural modes. The vibration modes are generally affected by the combined mass, stiffness, and damping characteristics of the containing fluid tube and the material contained therein. Material flows into the flow meter from a connected pipeline on the inlet side manifold of the vibrating meter. The material is then directed through the fluid tube or fluid tubes and exits the flow meter to a pipeline connected on the outlet side manifold.
Brace bars are used on flow meters to reduce stress on welded joints where the flow tubes are attached to the manifolds. The brace bars are typically affixed to the two flow tubes at a point between the driver location on the flow tubes and the welded joint that affixes the flow tubes to the manifold. A separate brace bar is affixed to the flow tubes at both the inlet and outlet sides of the tubes to fix the positions of the flow tubes with respect to one another. The brace bar defines a new pivot axis for the out-of-phase vibrations of the flow tubes. The brace bars are typically brazed to the flow tubes on the brace bar's inner circumference.
To effectively reduce the stress on the welded joints, it is important that the brazing between the flow tube and the brace bar is not flawed. Flaws can be prevented by minimizing the flow tube gap between the flow tubes in the brace bar. However, the flow tube gap must also be sufficient for the flow tubes to be inserted into the brace bar without damaging the flow tubes. The gaps sufficient to allow insertion of the flow tubes can lead to flaws such as voids. Once a void in the brazing material is discovered, the brace bar is typically discarded resulting in increased costs for the manufacturer. Similar problems occur with other coupling processes such as welding.
Accordingly there is a need to minimize the flow tube gap while allowing the flow tube to be inserted into the brace bar.